From 259ee0e7022ce15f4f2c8294a4fc3de7005d7fab Mon Sep 17 00:00:00 2001
From: fishsoupisgood <github@madingley.org>
Date: Mon, 29 Apr 2019 07:30:28 +0100
Subject: working with one set of stripes

---
 app/timex.c | 248 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 248 insertions(+)
 create mode 100644 app/timex.c

(limited to 'app/timex.c')

diff --git a/app/timex.c b/app/timex.c
new file mode 100644
index 0000000..40f43ad
--- /dev/null
+++ b/app/timex.c
@@ -0,0 +1,248 @@
+#include "project.h"
+
+/*
+ * VGA 640x480 mode timings are
+ *
+ * 48 640 16 96
+ * 10 480 33  2
+ *
+ * at 25.175 Hz
+ *
+ */
+
+/*
+ * Two bytes are shown per video frame one starting at
+ * scanline 70, the other at 255, and there are 15
+ * scanlines between bits.
+ *
+ */
+
+#define SL_BYTE_1_START 70
+#define SL_BIT    15
+#define SL_BYTE_2_START 255
+
+#undef PAD
+#undef EX
+
+#define SL_ON(byte,bit) ((SL_BYTE_ ## byte ## _START) + (SL_BIT * (bit)))
+#define SL_OFF(byte,bit) (SL_ON(byte,bit) + 1)
+
+
+#define SEND_BIT(byte,bit,data) \
+  case SL_ON(byte,bit): \
+  timex_led((data) & 1); \
+  break; \
+  case SL_OFF(byte,bit): \
+  timex_led(1); \
+  break
+
+#define SEND_BIT_SHIFT(byte,bit,data) \
+  case SL_ON(byte,bit): \
+  timex_led((data) & 1); \
+  data>>=1; \
+  break; \
+  case SL_OFF(byte,bit): \
+  timex_led(1); \
+  break
+
+#define SEND_BYTE(byte, start, data) \
+  SEND_BIT(byte,0,start); \
+  SEND_BIT_SHIFT(byte,1,data); \
+  SEND_BIT_SHIFT(byte,2,data); \
+  SEND_BIT_SHIFT(byte,3,data); \
+  SEND_BIT_SHIFT(byte,4,data); \
+  SEND_BIT_SHIFT(byte,5,data); \
+  SEND_BIT_SHIFT(byte,6,data); \
+  SEND_BIT_SHIFT(byte,7,data); \
+  SEND_BIT_SHIFT(byte,8,data)
+
+
+
+/*
+ * We ignore the horizontal front/back/sync and drive the system timer at
+ * the horizontal sync frequency of 31.46875kHz or as close as we can manage
+ */
+
+
+#define BUFFER_SIZE 512
+
+#define TIMEX_BANK GPIOB
+#define TIMEX_GPIO GPIO9
+
+ring_t timex_ring;
+static uint8_t timex_ring_buf[BUFFER_SIZE];
+
+
+static inline void timex_led (int v)
+{
+  if (v)
+    gpio_set (TIMEX_BANK, TIMEX_GPIO);
+  else
+    gpio_clear (TIMEX_BANK, TIMEX_GPIO);
+}
+
+
+#define SYNCS 200
+typedef enum  {
+  STATE_MAGIC1,
+  STATE_MAGIC2,
+  STATE_MAGIC3,
+  STATE_MAGIC4,
+  STATE_IDLE,
+  STATE_SYNC1,
+  STATE_SYNC2,
+  STATE_PACKET_HEADER,
+  STATE_PACKET_DATA,
+  STATE_PACKET_PAD,
+  STATE_PACKET_RECOVERY,
+
+} Timex_state;
+
+
+
+static int get_data (uint8_t *start, uint8_t *data)
+{
+  static Timex_state state = STATE_MAGIC1;
+  static unsigned len;
+  static unsigned pad;
+
+
+  *start = 0;
+
+  switch (state) {
+  case STATE_MAGIC1:
+    if (ring_empty (&timex_ring))
+      return 1;
+    
+  case STATE_IDLE:
+    if (ring_empty (&timex_ring))
+      return 1;
+
+    state = STATE_SYNC1;
+    len = SYNCS;
+    break;
+
+  case STATE_SYNC1:
+    *data = 0x55;
+    len--;
+
+    if (!len) state = STATE_SYNC2;
+
+    break;
+
+  case STATE_SYNC2:
+    *data = 0xaa;
+    state = STATE_PACKET_HEADER;
+    break;
+
+  case STATE_PACKET_HEADER:
+    if (ring_read_byte (&timex_ring, data)) {
+      /*No more data*/
+      state = STATE_MAGIC1;
+      return 1;
+    }
+    len = *data -1 ;
+    state = STATE_PACKET_DATA;
+#ifdef PAD
+    pad =(*data &1);
+#else
+    pad=0;
+#endif
+    break;
+
+  case STATE_PACKET_DATA:
+    ring_read_byte (&timex_ring, data);
+    len--;
+
+    if (!len) {
+#ifdef PAD
+      len = 20;
+#else
+      len = 10;
+#endif
+
+      if (pad)
+      state = STATE_PACKET_PAD;
+	else 
+      state = STATE_PACKET_RECOVERY;
+    }
+
+    break;
+
+  case STATE_PACKET_PAD:
+	*data=0x00;
+      state = STATE_PACKET_RECOVERY;
+	break;
+
+
+  case STATE_PACKET_RECOVERY:
+    *start = 1;
+    *data = 0xff;
+    len--;
+
+    if (!len) state = STATE_PACKET_HEADER;
+
+    break;
+  }
+
+
+  return 0;
+}
+
+void timex_tick (void)
+{
+  static unsigned line = 0;
+  static uint8_t data, start;
+
+
+  switch (line) {
+  case (SL_BYTE_1_START-2):
+    if (get_data (&start, &data)) {
+      line = 0;
+      return;
+    }
+    break;
+
+    SEND_BYTE (1, start, data);
+
+#ifdef PAD
+  case (SL_BYTE_2_START-2):
+    if (get_data (&start, &data)) {
+      line = 0;
+      return;
+    }
+    break;
+    SEND_BYTE (2, start, data);
+#endif
+
+
+  }
+
+
+  line++;
+
+  if (line == 525)
+    line = 0;
+}
+
+#ifdef EX
+uint8_t ex[]={
+#include "/root/projects/timex_datalink/datalink-1.0.1/fish.h"
+};
+#endif
+
+	
+
+
+void
+timex_init (void)
+{
+  ring_init (&timex_ring, timex_ring_buf, sizeof (timex_ring_buf));
+#ifdef EX
+  ring_write(&timex_ring,ex,sizeof(ex));
+#endif
+  gpio_set_mode (TIMEX_BANK, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, TIMEX_GPIO);
+
+
+  timex_led (1);
+}
-- 
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